The present invention relates to an output section of an integrated logic circuit, and particularly to an input/output section through which a logic input or output signal is transferred from the outside into the internal logic circuit or from the latter to the outside.
In accordance with the recent development of electronics, the application field thereof is being rapidly broadened and also demand for diversification of circuits is increased. In the prior art, an N-channel type integrated circuit sufficed only to be connected to a transistor of the same conduction type, that is, N-channel type field effect transistor. However, because of this diversification it has become sometimes necessary for the N-channel field effect transistor to be connected to a transistor of a different conduction type, that is, P-channel type field effect transistor. However, it is not always easy to connect integrated circuits having transistors of different conduction types to each other.
For instance, in some cases, exchange of data is effected bidirectionally between a microprocessor IC and a memory IC or an I/O controller IC through a data bus line. More particularly, output transistors are provided within the respective IC's and the output signals of the respective IC's are transferred to the data bus line via the respective output transistors, while input signals from the data bus line are directly supplied to the respective IC's through respective external input/output terminals of the IC's to which the respective output transistors are connected, but not through the output transistors. With such input/output section, the output transistor of the IC is kept cut-off when that IC receives a signal from the data bus, and the signal is transmitted into the data bus from an output transistor of another IC.
Such a direct connection via the data bus line can be easily formed where the connected IC's have their output transistors of the same conduction type. Where the respective output transistors are of different conduction types, however, the direct connection cannot be formed unless an inverter is specially added to one of the output sections. Since the conduction type of the output transistor is usually the same as that of the transistors employed in the IC's, the polarity of an IC which can be connected to another IC is determined by the polarity of the latter IC. In other words, it was impossible to interconnect IC's having transistors of any arbitrary type of conductivity.